text: This is an outline of an example mechanism of yeast cells by which chromatin structure and histone post-translational modification help regulate and record the transcription of genes by RNA polymerase II.
  This pathway gives examples of regulation at these points of transcription:
  * Pre-initiation (promotion by Bre1, histone modification)
  * Initiation (promotion by TFIIH, Pol II modification and promotion by COMPASS, histone modification)
  * Elongation (promotion by Set2, Histone Modification)
  This refers to various stages of the process as regulatory steps. It has not been proven that they are used for regulation, but is very likely they are.
  RNA Pol II elongation promoters can be summarised in 3 classes.
  #Drug/sequence-dependent arrest-affected factors (Various interfering proteins)
  #Chromatin structure-oriented factors (Histone posttranscriptional modifiers, e.g., Histone Methyltransferases)
  #RNA Pol II catalysis-improving factors (Various interfering proteins and Pol II cofactors; see RNA polymerase II).